Broadly speaking, it is known to provide a filter having a plurality of elements with some arrangement for the purpose of reversing flow selectively through the elements so as to clean the elements, at least partially, and so as to remove the material filtered out of a liquid medium passing therethrough.
In one known filter of this general type, shown in German Auslegeschrift No. 1,029,995, the filter elements are in the general configuration of a battery and the separation device consists of separate rotary valves associated with each end of each filter element, the valves being connected nonrotatably with each other by means of a shaft which is coaxial with the filter element, the valves being driven by means of a control device of the sort that is opened when one of the rotary valves at the other end is closed. Such a configuration is expensive and complicated because of the plurality of rotary valves and the reversing devices associated with each pair of such valves.
With another known reversible flow filter, shown in German Patent No. 14 86 812, the filter elements are arranged in a circle. The separation device has passage openings in the separation plates connected with the filter element being covered or freed and rotary valves connected nonrotatably with each other. The rotary valves work together on any one of the filter elements and are hollow, which leads to a complicated structure.